Monsoon influence on planktic δ18O records from the South China Sea

While the benthic delta O-18 records from many South China Sea sites mimic the SPECMAP/LRO4 standard, their paired planktic delta O-18 curves differ by comparable values at negative peaks corresponding to interstadials, especially between MIS 5.1, 53, 5.5, 6.5, and 73. Similar planktic delta O-18 records also occur in some other low-latitude oceans under monsoon influence. Because neither temperature nor salinity effects can fully account for the variations of such delta O-18 records after derivation from the SPECMAP/LRO4 standard, variations in the rain water 8180 affected by regional hydroclimate changes are considered to have played an important role. In contrast to the SPECMAP/LRO4 standard delta O-18 curve prevailed by 100-kyr cycles, these regional planktic delta O-18 curves are distinguished by 20-kyr precession signal, showing partial similarity to the delta O-18 records of atmospheric oxygen in polar ice-core bubbles and in stalagmite calcite. We speculate that the common features of these three independent delta O-18 records are indicative of the effect of evolving hydrological cycling driven by monsoon circulation in low latitudes. (C) 2016 Elsevier Ltd. All rights reserved.